TW201815589A - Surface protective film - Google Patents

Abstract

The present invention addresses the problem of providing a surface protective film which is resistant to discoloration, expansion and the like caused by the penetration of a plasticizer. A surface protective film having, on the outermost surface thereof, a protective layer made of polycarbonate polyurethane is provided as the solution of the problem.

Description

Surface protection film

The invention relates to a surface protection film for protecting a transparent substrate on a display surface.

In a portable electronic device with a display, such as a smart phone, a personal computer (PC), and a music player, a surface protective film may be attached to protect a transparent substrate on the surface of the display. The surface protection film requires light transmittance, transparency, abrasion resistance, weather resistance, and the like. In addition, in recent years, portable electronic devices are usually operated by electrostatic capacitance type touch panels, and anti-fouling properties that are not easy to stick to sebum, the stylus feel of the stylus, the sliding property, and the pressure of the front end of the stylus are newly required. The inserted film returns to its original self-healing properties over time.

As a surface protective film, for example, Patent Document 1 proposes a protective film having a transparent substrate film having, on one side thereof, a (meth) acrylic acid urethane, a fluorine-containing compound, and / or a siloxane bond. A soft resin layer made of a compound. Patent Document 2 proposes an invention of a self-healing laminate including a base film and a self-healing resin layer. In addition, as Patent Document 3, the applicant and the like have proposed a surface protective film which is sequentially laminated with a heat cured product which is a cured product of a polyether polyol, an aliphatic isocyanate, an alcohol-based hardener, and a non-amine catalyst. A protective polyurethane layer, a transparent base film, and an adhesive layer.

A portable electronic device is wound with a cord of a headphone, or inside a bag, etc., and comes in contact with various plastic products such as a charger, a universal serial bus (USB) cable, stationery, and cosmetics. If the plastic product is in contact with the surface protective film, the plasticizer contained in the plastic product penetrates the surface protective film, and the surface protective film may be discolored and swelled. In particular, rubber products such as USB cables and earphone cords contain a large amount of plasticizers, so it is easy to cause discoloration and swelling of the surface protection film due to contact. [Prior Art Literature] [Patent Literature]

[Patent Literature 1] Japanese Patent Laid-Open No. 2012-196868 [Patent Literature 2] Japanese Patent Laid-Open No. 2013-27998 [Patent Literature 3] International Publication No. 2017/094480

[Problems to be Solved by the Invention] An object of the present invention is to provide a surface protective film which is hard to cause discoloration, swelling, and the like due to penetration of a plasticizer. [Means for solving problems]

The configuration of the present invention for solving the above problems is as follows. A surface protection film comprising a protective layer made of a polycarbonate-based polyurethane on the outermost surface. 2. The surface protective film according to 1., wherein at least three layers of the protective layer, a transparent substrate film, and an adhesive layer are laminated in this order. 3. The surface protective film according to 1. or 2., wherein the polycarbonate-based polyurethane is a material composition containing a polycarbonate-based polyol, an isocyanate, and an alcohol-based hardener Hardened. 4. The surface protective film according to any one of 1. to 3., wherein the protective layer includes a silicon-based additive. 5. The surface protective film according to any one of 1. to 4, wherein a thickness of the protective layer is 50 μm or more and 300 μm or less. 6. The surface protective film according to any one of 1. to 5., wherein the haze value is 0.1% or more and 40% or less. A surface protective film laminate, comprising: a release film on the protective layer side surface area layer of the surface protective film according to any one of 1. to 6 .; and Release film. A method for producing a surface protective film, the surface protective film being characterized by having a protective layer made of polycarbonate-based polyurethane on the outermost surface thereof, and the method for producing the surface protective film being characterized by : Feeding a material composition containing a polycarbonate-based polyol, an isocyanate, an alcohol-based hardener, and a catalyst into the gaps of the first and second gap maintaining members output by a pair of rollers disposed at intervals, The material composition is thermally cured while being held between the first and second gap maintaining members to form the protective layer. 9. The method for producing a surface protective film according to 8., wherein one of the first and second gap maintaining members is a transparent base film of a surface protective film. 10. The method for manufacturing a surface protective film according to 8. or 9, wherein the material composition includes a silicon-based additive. 11. The method for producing a surface protective film according to any one of 8. to 10., wherein one of the first and second gap maintaining members is a film not subjected to a release treatment, and the other One is a film subjected to a release treatment. 12. The method for producing a surface protective film according to any one of 8. to 11., wherein the other of the first and second gap maintaining members is a film having unevenness, and the unevenness is used. Surface to hold the material composition. [Effect of the invention]

The surface protection film of this invention has a protective layer which consists of a polycarbonate-type polyurethane on the outermost surface. Regarding the surface protective film of the present invention, even if the protective layer is in contact with a plastic product, the plasticizer is difficult to penetrate, and it is difficult to cause discoloration, swelling, and the like. The surface protective film of the present invention is excellent in light transmittance, transparency, scratch resistance, weather resistance, and self-healing property. In addition, the surface protection film of the present invention is excellent in operability of the stylus pen and has a writing feeling like writing on paper with a pen. Furthermore, the surface protection film of the present invention containing a silicon-based additive has good sliding properties, and can be operated very comfortably with a touch panel such as a stylus pen or a finger. The surface protection film of the present invention can also form irregularities on the outermost surface of the protective layer, thereby imparting anti-glare properties. In addition, although the protective layer of the surface protective film of the present invention has a thickness of 50 μm or more and 300 μm or less, it has optical characteristics that can be used as a surface protective film.

A surface protection film laminate formed by laminating a release film and a release film on the surface protection film of the present invention can prevent dirt, damage, and the like of the protection layer, and is therefore excellent in handleability. According to the manufacturing method of this invention, a surface protection film can be manufactured continuously. Furthermore, a protective layer having a thickness of 50 μm or more and 300 μm or less, which is difficult to produce by a wet coating method, can be produced without reducing optical characteristics. In addition, unevenness can be easily formed on the surface of the protective layer by a transfer method.

The protective film of this invention is characterized by having the protective layer which consists of a polycarbonate-type polyurethane on the outermost surface. FIGS. 1 and 2 respectively show a surface protective film 10 as an embodiment of the present invention and a state in which the surface protective film 10 as an embodiment is bonded to a transparent substrate 20 on a display surface. In addition, in FIGS. 1 and 2, the thickness of each layer does not refer to the actual thickness.

The surface protection film 10 as an embodiment is characterized in that three layers of a protective layer made of polycarbonate-based polyurethane, a transparent base film, and an adhesive layer 3 are laminated in this order. In addition, the surface protection film 10 as an embodiment is bonded to the transparent substrate 20 on the outermost surface of the display via the adhesive layer 3. As described above, the surface protection film of the present invention is adhered to the surface of the transparent substrate to prevent damage, cracks, dirt, and the like of the transparent substrate.

"Protective layer" The protective layer is made of a polycarbonate-based polyurethane. The polycarbonate-based polyurethane refers to a urethane using a polycarbonate-based polyol as a polyol component.

a. Polycarbonate polyol As the polycarbonate polyol, for example, a reaction product of a dialkyl carbonate and a diol is mentioned. Examples of the dialkyl carbonate include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethyl carbonate. Wait. These may be used alone or in combination of two or more.

Examples of the diol include 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8 -Octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, 2-ethyl-1,6-hexanediol, 3 -Methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, neopentyl glycol, 1,3-cyclohexanediol, 1,4-cyclohexanediol , 1,4-cyclohexanedimethanol, 2,2'-bis (4-hydroxycyclohexyl) -propane and the like. These may be used alone or in combination of two or more. The diol is preferably an alicyclic or alicyclic diol having 4 to 9 carbon atoms. For example, it is preferable to use alone or in combination of two or more kinds of 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 1,4-ring Hexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, and 1,9-nonanediol. A diol having no branched structure is more preferred.

In addition, as the polycarbonate-based polyol, for example, a polycarbonate diol, a polycarbonate triol, a polycarbonate tetral, a derivative in which a side chain or a branched structure is introduced, or a modified body may be used. , And mixtures of these.

The number average molecular weight of the polycarbonate-based polyol is preferably 200 or more and 10,000 or less, more preferably 500 or more and 5,000 or less, and even more preferably 800 or more and 3,000 or less. If the number average molecular weight is less than 200, the reaction may be too fast, the handling may be poor, and the molded product may lose its flexibility and become brittle. On the other hand, if the number average molecular weight is more than 10,000, the viscosity may become too high, the handleability may be poor, and the formed article may crystallize and become cloudy. In the present invention, the number average molecular weight refers to a molecular weight calculated from a hydroxyl value of a polyol measured based on Japanese Industrial Standards (JIS) -K1557. In addition, even if it is outside the said numerical range, unless it deviates from the meaning of this invention, it is not excluded.

b. Isocyanate As the isocyanate, an isocyanate having two or more isocyanate groups in the molecule can be used without particular limitation. For example, toluene diisocyanate, ditoluidine diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, carbodiimide diphenylmethane polyisocyanate, and crude diphenylmethane diisocyanate can be used. , Xylylene diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate Isocyanate, dimer acid diisocyanate, norbornene diisocyanate, etc. Of these, two or more kinds may be used in combination.

The polycarbonate-based polyurethane forming the protective layer of the present invention preferably uses an aliphatic isocyanate having no aromatic ring as an isocyanate component. Polyurethanes obtained from aliphatic isocyanates are difficult to cause yellowing, and light or heat from light sources, sunlight, etc. can prevent the polyurethanes from discoloring and reducing transparency.

c. Alcohol-based hardener The polycarbonate-based polyurethane that forms the protective layer of the present invention uses an alcohol-based hardener as a hardener. Compared with amine-based hardeners, alcohol-based hardeners have less adverse effects on the human body and the environment.

The alcohol-based hardener can be used without particular limitation as long as it has two or more hydroxyl groups in the molecule. Examples include ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, Pentylene glycol (2,2-dimethyl-1,3-propanediol), 1,6-hexanediol, polyethylene glycol, polypropylene glycol, polybutanediol, cyclohexanedimethanol, hydrogenated bisphenol A Glycerol, Glycerol, Trimethylolpropane, Butanetriol, Glycerol, Hexatriol, Cyclotriol, Cyclotriol, Triols, Pentaerythritol, Dipentaerythritol, Tetramethylol Alcohols such as propane and ternary. Among these, it is preferable to use a diol alone or to use a diol and a triol together. When the amount of the trihydric alcohol is large, the strength of the obtained polyurethane is lowered. Therefore, it is preferable to use the diol in the range of 50 to 100 parts by weight, and the amount of 50 to 0 parts by weight. A trihydric alcohol is used in a range, and a glycol is preferably used in a range of 60 parts by weight to 80 parts by weight, and a triol is used in a range of 40 parts by weight to 20 parts by weight. From the viewpoints of handleability and mechanical properties, 1,4-butanediol as a diol and trimethylolpropane as a triol are preferred.

d. Catalyst The polycarbonate-based polyurethane forming the protective layer of the present invention is preferably thermally cured in the presence of a non-amine-based catalyst. By using a non-amine-based catalyst, a polyurethane having excellent non-coloring properties, transparency, and weather resistance can be obtained. On the other hand, the polyurethane hardened by an amine catalyst may emit yellow light, and the appearance may be colored over time. Examples of the non-amine catalyst include organic tin compounds such as di-n-butyltin dilaurate, dimethyltin dilaurate, dibutyltin oxide, and octane tin; organic titanium compounds; organic zirconium compounds; and tin carboxylates. Salt, bismuth carboxylate and the like. Among these, an organotin compound is preferable because it is easy to adjust the reaction rate. The non-amine-based catalyst is preferably added so as to be 0.0005 wt% or more and 3.0 wt% or less with respect to the total amount of a. To c. If it is less than 0.0005% by weight, the reaction rate may not be sufficiently fast, and a molded body may not be obtained efficiently. If it is more than 3.0% by weight, there are cases in which the reaction speed becomes too fast, a molded body with a uniform thickness cannot be obtained, the heat resistance or weather resistance of the molded body is reduced, the light transmittance is reduced, and the molded body is colored. In addition, even if it is outside the said numerical range, unless it deviates from the meaning of this invention, it is not excluded.

The polycarbonate-based polyurethane forming the protective layer may contain a colorant, a light stabilizer, a heat stabilizer, an antioxidant, a mildew-proof agent, and a flame retardant, as long as the required characteristics are not hindered. , Lubricants and other additives.

e. Silicone-based additive In the surface protective film of the present invention, the polycarbonate-based polyurethane forming the protective layer preferably contains a silicon-based additive. Since the protective layer contains a silicon-based additive, the sliding property is improved, and a touch panel operation using a stylus or a finger can be performed comfortably. A silicon-based additive may be added to the polycarbonate-based polyurethane material composition before thermal curing, and the material composition may be thermally cured to be contained in the protective layer. In addition, the silicon-based additive is preferably a non-reactive one that does not form a covalent bond with an interconnection network formed by a polycarbonate-based polyol, an isocyanate, and an alcohol-based hardener. The non-reactive silicon-based additive slowly oozes to the outermost surface of the protective layer, so it can provide sliding properties for a long time. The silicon-based additive can be used without particular limitation as long as it does not phase-separate from the material composition before heat curing. For example, polyether modified polydimethylsiloxane, polyaralkyl modified polydimethylsiloxane, and long chain alkyl modified polydimethylsiloxane can be used. Specifically, KF352A, KF615A, X22-4515, KF410, KF412, and the like manufactured by Shin-Etsu Silicone Co., Ltd., which are commercially available products, can be used.

The protective layer is a molded body composed of a polycarbonate-based polyurethane formed by curing a material composition containing a polycarbonate-based polyol, an isocyanate, and an alcohol-based hardener using a catalyst. It may be any of a one-shot method, a prepolymer method, and a quasi-prepolymer method. The protective layer may contain any additive such as a silicon-based additive.

In a one-step method, a polycarbonate-based polyol, an isocyanate, an alcohol-based hardener, an optional additive, and a catalyst may be added and cured at one time to produce a polycarbonate-based polyurethane molded body. . In the prepolymer method, as long as a polycarbonate-based polyurethane molded article is produced, a polycarbonate-based polyol is allowed to react with an excess of isocyanate in stoichiometry. A prepolymer having an isocyanate group at a terminal is prepared in advance, and a predetermined amount of an alcohol-based hardener, an optional additive, and a catalyst are mixed therein to harden the prepolymer. In the quasi-prepolymer method, as long as a polycarbonate-based polyurethane molded article is produced, a part of the polycarbonate-based polyol is mixed with an alcohol-based hardener in advance, and the remainder is used. The polycarbonate-based polyol and the aliphatic polyisocyanate are used to prepare a prepolymer, and a mixture of the polycarbonate-based polyol and an alcohol-based hardener, an optional additive, and a catalyst, which have been mixed in advance, is used for curing.

In the present invention, the molar number of the hydroxyl group (-OH) contained in the alcohol-based hardener in the polycarbonate-based polyurethane material composition before heat curing is equal to the aliphatic polyisocyanate or prepolymer The molar ratio (-OH / -NCO: hereinafter referred to as the α ratio) of the isocyanate group (-NCO) of the product is preferably 0.8 or more and 1.5 or less. If it is less than 0.8, the mechanical properties will become unstable, and if it is more than 1.5, the surface adhesion will increase, which will damage the good brushing experience. The polycarbonate-based polyurethane preferably does not contain an acrylic skeleton (acrylic skeleton or methacrylic skeleton). That is, it is preferable that the polycarbonate-type polyurethane which forms the protective layer of this invention does not contain acrylic modified polyurethane. Polycarbonate polyurethane having an acrylic skeleton may impair the flexibility of the polyurethane, and at the same time may reduce mechanical strength such as abrasion resistance and tear strength. In addition, the acrylic skeleton or Residues of the catalyst used to introduce the acrylic skeleton cause coloration of the emitted light.

The thickness of the protective layer is preferably 50 μm or more and 300 μm or less. With the protective layer having a thickness of 50 μm or more and 300 μm or less, the stylus feel and sliding properties of the stylus become very good. If the thickness of the protective layer is less than 50 μm, the pen-feeding feeling and self-healing property are reduced. If the thickness of the protective layer is greater than 300 μm, the light-transmitting, transparency, pen-like feeling, sliding property, and self-healing property are reduced. It is difficult to make use of uniform thickness molding. When it is 50 μm or more and 300 μm or less, the performance required for the surface protective film can be well balanced, and it can be easily manufactured.

The surface protection film of the present invention has a haze value of 0.1% or more and 40% or less, and a total light transmittance of 90% or more. If the fog value is greater than 40% or the total light transmittance is less than 90%, the visibility of the display is reduced. When the haze value of the surface protective film is 0.1% or more and less than 3%, the transparency is excellent and a clear appearance can be obtained. When the haze value of the surface protection film is 3% or more and 40% or less, anti-glare property can be imparted to the surface protection film. In addition, a surface protective film having anti-glare properties makes it difficult to show scratches attached to the surface of the protective layer. In order to set the haze value of the surface protection film to 3% or more and 40% or less, it is only necessary to form irregularities on the outermost surface of the protective layer. The concave-convex shape of the outermost surface of the protective layer is not particularly limited as long as it has the haze value and the total light transmittance, and may be appropriately adjusted in accordance with the refractive index, light absorption, etc. of the material used. In general, the average length (RSm) of the roughness curve element is about 10 μm or more and 80 μm or less. The arithmetic mean roughness Ra is about 0.01 μm to about 0.3 μm, and the maximum height Rz is about 0.1 μm to 2.0 μm.

"Transparent substrate film" The transparent substrate film is a protective substrate. As long as the material constituting the transparent base film is excellent in transparency, flexibility, and mechanical strength, it can be used without particular limitation, and polyethylene terephthalate (PET), polyethylene Polyethylene naphthalate (PEN), polycarbonate (PC), Cyclo olefin polymer (COP), polyimide (PI), etc. The thickness of the transparent base film is preferably 50 μm or more and 500 μm or less. The protective layer of the surface protective film of the present invention is composed of a polycarbonate-based polyurethane. The thermal expansion coefficient of the polycarbonate-based polyurethane that forms the protective layer is usually larger than the thermal expansion coefficient of the material constituting the transparent base film. Therefore, if the thickness of the transparent base film is less than 50 μm, it is protected by low temperature. The shrinkage of the layer may cause an inward stress to the end portion of the transparent base film, which may cause the surface protection film to peel from the transparent substrate. If the thickness of the transparent base film is more than 500 μm, the surface protection film becomes bulky and the cost increases. In addition, operability is reduced when it is bonded to a touch panel display surface. In addition, although it demonstrates in detail in the following "the manufacturing method of a protective layer", a protective layer may be directly shape | molded on a transparent base film. In this case, in order to prevent deformation when the material composition is heated by thermosetting, the transparent base film is preferably thick. In addition, even if it is outside the said numerical range, unless it deviates from the meaning of this invention, it is not excluded.

“Adhesive layer” The adhesive layer is used to adhere the surface protection film of the present invention to the transparent substrate on the outermost surface of the display. The type of the adhesive is not particularly limited, and an acrylic resin, an epoxy resin, a urethane resin, and a silicon resin can be used. Among these, even if it is a surface substrate which has been subjected to a surface treatment such as an antifouling treatment or a low reflection treatment, an acrylic resin can be attached. In addition, silicon-based resins have excellent wetting properties, are less likely to generate bubbles when attached to a transparent substrate, have good re-peelability, and are less likely to generate adhesive residues when peeled. The thickness of the adhesive layer is usually within a range of 5 μm or more and 60 μm or less, but can be appropriately adjusted according to the required specifications.

In order to protect the surface protection film of the present invention from production to attachment to a transparent substrate, a release film can be pasted on the surface of the protective layer side of the surface protection film, and a release film can be pasted on the other surface to make a surface protection film laminate. body. FIG. 3 shows a surface protection film laminate 30 in which a release film 4 and a release film 5 are adhered to a surface protection film 10 as an embodiment. It should be noted that the thickness of each layer in FIG. 3 does not mean the actual thickness.

The release film is used to prevent dirt or dust from being deposited on the protective layer, and it is preferable to use a film that has been subjected to a release treatment on the surface on the bonding side. When the release film subjected to the release treatment is peeled from the protective layer, the release agent migrates from the release film to the surface of the protective layer, and the sliding surface of the protective layer can be imparted to the surface of the protective layer shortly after the release film is peeled off. Touch operation. In addition, although described in detail in "the manufacturing method of a protective layer" below, a protective layer may be directly shape | molded on a release film. At this time, in order to prevent deformation when the material composition is heated by thermosetting, the release film is preferably 50 μm or more and 300 μm or less, and more preferably thick.

The release film protects the surface on the opposite side of the protective layer side of the outermost surface protective film, and for example, protects the adhesive layer. As the release film, a film obtained by releasing the surface of the bonding side can be preferably used. In the embodiment shown in FIG. 3, the adhesive layer 3 is protected, and dirt, dust adhesion, and a decrease in adhesion are prevented.

"Manufacturing method of protective layer" The protective layer is produced by containing at least a polycarbonate polyol, an isocyanate (or a urethane prepolymer composed of these), an alcohol-based hardener, and optionally Additives and non-amine catalyst material composition are fed into the gap of the gap maintaining member output by a pair of rollers spaced apart, and the material composition is introduced to the heating state while being held between the gap maintaining members. The device is thermally cured.

FIG. 4 is a schematic diagram showing a method for manufacturing a protective layer. Hereinafter, the manufacturing method of a protective layer is demonstrated using FIG. A material composition 40a containing at least a polycarbonate-based polyol, an isocyanate (or a urethane prepolymer made of these), an alcohol-based hardener, any additives, and a non-amine catalyst is passed through The casting machine 41 flows into the gaps of the first and second gap maintaining members 42a and 42b output by the pair of conveyance rollers 43a and 43b arranged at a distance. The first and second gap maintaining members 42a and 42b are introduced into the heating device 46 with the material composition 40a held therebetween. The material composition 40a is thermally cured while being held between the first and second gap maintaining members 42a and 42b, thereby forming a sheet 40 of a polycarbonate-based polyurethane. In addition, in FIG. 4, 44 is a conveying roller for outputting the first and second gap maintaining members 42 a and 42 b, 45 is an auxiliary roller, and 47 is a first for the holding material composition 40 a in the heating device 46. And the second gap maintaining members 42a and 42b.

The first and second gap maintaining members 42a and 42b can be used without particular limitation as long as they are materials that do not undergo thermal deformation when the material composition is thermally cured. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), cyclic olefin resin (COP), and polyimide (PI) can be used. ) And other polymer materials. In the schematic diagram shown in FIG. 4, as the gap maintaining member, a long film made of a polymer material is used, but an endless belt made of these polymer materials or a metal material such as aluminum may also be used.

The first and second gap maintaining members 42a and 42b are conveyed by stretching with the same tension while holding the material composition 40a therebetween, so that the gap can be maintained at a fixed size. The material composition 40a is sandwiched between the first and second gap maintaining members 42a and 42b, and is hardened while maintaining a fixed thickness, so that it becomes a polycarbonate-based polyurethane sheet excellent in thickness accuracy. 40. With this manufacturing method, a sheet 40 having a thickness of 30 μm or more, which is difficult to achieve by coating, and having practical optical characteristics as a surface protective film for a display can be continuously formed.

The position of the head portion 41a of the casting machine 41 is preferably biased toward any of the conveying rollers compared to the central portions of the conveying rollers 43a, 43b (the central portions of the gap formed by the first and second gap maintaining members 42a, 42b). Side, and preferably, the distance is less than the radius of the conveying roller. That is, the head 41 a of the casting machine 41 is preferably located between the central portion of the pair of transfer rollers 43 a and 43 b and the central axis of one of the transfer rollers. The shortest distance between the front end portion of the head portion 41a and the surface of the transfer roller is preferably 5 cm or less. By disposing the head portion 41a in the manner described above, the thickness accuracy of the polycarbonate-based polyurethane sheet 40 is further improved, and it is difficult for air bubbles to mix into the first and second gap maintaining members 42a, 42b. The uncured material composition 40a of the gap is easy to escape.

The conveyance rollers 43a and 43b may have only a conveyance function, but a heating roller is preferable. If the conveying roller is a heating roller, the material composition 40a can be held in the gap between the first and second gap maintaining members 42a and 42b and then cured shortly, and the thickness can be maintained more uniformly until the material composition 40a is introduced into the heating. Up to the inside of the device 46, a polyurethane sheet 40 having more excellent thickness accuracy can be formed. The conveying surface temperature when the conveying roller is heated is preferably set to 10 ° C to 60 ° C. When the temperature is less than 10 ° C, the viscosity of the material composition 40a becomes high and bubbles cannot escape, and the curing reaction becomes slower, resulting in a decrease in the thickness accuracy of the sheet 40. If it exceeds 60 ° C., the material composition 40 a may be hardened on the transfer roller or the air bubbles may enter the sheet 40.

The heating device 46 is a heating furnace provided with a heater, as long as it is a heating device that can increase the temperature in the furnace to the hardening temperature of the material composition 40a. In addition, the heating conditions (hardening conditions) in the heating device 46 are not particularly limited, and may be appropriately set according to the composition of the material composition 40a. can.

The self-heating device 46 carries out a long laminated body composed of the first gap maintaining member 42a, the polycarbonate-based polyurethane sheet 40, and the second gap maintaining member 42b. The sheet 40 is the protective layer 1 of the surface protective film of the present invention.

"Manufacturing method of surface protection film laminated body" In the said manufacturing method, one of the 1st gap maintenance member 42a and the 2nd gap maintenance member 42b can be made into the transparent base film 2. The other of the first gap maintaining member 42 a and the second gap maintaining member 42 b may be the release film 4. Hereinafter, a case where the first gap maintaining member 42a becomes the transparent base film 2 and the second gap maintaining member 42b becomes the release film 4 will be described as an example.

According to the manufacturing method, the first gap maintaining member 42a serving as a transparent base film, the sheet 40 of polycarbonate-based polyurethane serving as a protective layer, and the second gap maintaining serving as a release film are carried out. A long laminated body constituted by the member 42b. At this time, it is preferable that the first gap maintaining member 42a to be a transparent base film is a film not subjected to a release treatment, and the second gap maintaining member 42b to be a release film is a film subjected to a release treatment.

The adhesive layer 3 is formed on the surface of the first gap maintaining member 42 a of the long laminated body carried out from the heating device by coating, and a release film 5 is adhered to the adhesive layer 3 to obtain a long strip. The surface protection film laminated body 30 of this invention. In addition, a laminated body in which a transparent base film, an adhesive layer, and a release film are sequentially laminated may be used as the first gap maintaining member 42a. Furthermore, by using a film having unevenness as the second gap maintaining member 42b and using a surface retaining material composition 40a having unevenness, the unevenness can be transferred to the outermost surface of the sheet 40, and the obtained protective layer can be imparted. Anti-glare.

With this manufacturing method, a so-called roll-to-roll continuous production of the surface protective film laminate 30 can be performed. The manufactured surface protection film laminate 30 is provided with a release film 4 and a release film 5 on both sides, so that the surface protection film 10 can be prevented from being scratched, contaminated, and the like, and has excellent handleability.

The surface protective film laminated body can be rolled into a roll and shipped, or it can be shipped after being cut into a sheet. Alternatively, the long laminated body composed of the first gap maintaining member 42a, the polycarbonate-based polyurethane sheet 40, and the second gap maintaining member 42b or the laminated body may be cut and shipped. In the display factory or the like, the adhesive layer 3 is formed by coating, and is bonded to the transparent substrate of the display. [Example]

Hereinafter, the present invention will be further described in detail with examples, but the present invention is not limited to these examples. "Example 1" 100 g of poly (1,6-hexanecarbonate) glycol (manufactured by Tosoh Corporation, trade name: 980R) with a molecular weight of 2000 and a hydroxyl value of 55 was added, and 52.4 g Isophorone diisocyanate, 16.0 g of an alcohol-based hardener composed of a weight ratio of 1,4-butanediol / trimethylolpropane = 60/40, and 250 ppm as a non-amine catalyst An organotin compound is stirred and mixed to prepare a material composition. Thereafter, a 125 μm-thick PET film subjected to silicon treatment was used as a release film, a 100 μm-thick PET film was used as a transparent base film, and a silicon-based adhesive with a thickness of 50 μm was used as the adhesive layer. A silicon-treated PET film having a thickness of 75 μm was used as a release film, and the above-mentioned forming method was used to obtain a surface protective film laminate 1 having a protective layer (thickness: 100 μm) made of polycarbonate-based polyurethane.

"Example 2" As a polyol component, poly (3-methylpentane / 1,6-hexanecarbonate) diol (manufactured by Kuraray Co., Ltd.) having a molecular weight of 2000 and a hydroxyl value of 58 was used. , Trade name: C2090), and was performed in the same manner as in Example 1 except that isophorone diisocyanate was 53.2 g and alcoholic hardener was 16.1 g with respect to 100 g of polyol. A surface protective film laminate 2 having a protective layer (thickness: 100 μm) made of polycarbonate-based polyurethane was obtained.

"Comparative Example 1" Polytetramethylene ether glycol (Mitsubishi Chemical Corporation, product name: PTMG1500) having a molecular weight of 1500 and a hydroxyl value of 75 was used as the polyol component, and 100 g of the polyol was used. The diphenylmethane diisocyanate was 37.1 g, and the alcohol-based hardener composed of a weight ratio of 1,4-butanediol / trimethylolpropane = 80/20 was 7.0 g. The Example 1 was carried out in the same manner to obtain a surface protective film laminate 3 having a protective layer (thickness: 100 μm) made of a polyether-based polyurethane.

"Comparative Example 2" As a polyol component, poly (caprolactone) diol (manufactured by Daicel Co., Ltd., product name: Placcel 220) having a molecular weight of 2000 and a hydroxyl value of 56 was used. ) And an alcohol-based hardener composed of a diphenylmethane diisocyanate of 53.6 g and a weight ratio of 1,4-butanediol / trimethylolpropane = 75/25 with respect to 100 g of the polyol. A surface protective film laminate 4 having a protective layer (thickness: 100 μm) made of polycaprolactone-based polyurethane was obtained in the same manner as in Example 1 except that the amount was 14.1 g. .

"Comparative Example 3" Polyethylene adipate glycol having a molecular weight of 2000 and a hydroxyl value of 56 was used as a polyol component (manufactured by Sanyo Chemical Industry Co., Ltd., trade name: sanesta 2060) In addition, the diphenylmethane diisocyanate was set to 60.1 g, and the alcohol-based hardener composed of a weight ratio of 1,4-butanediol / trimethylolpropane = 80/20 was set to 16.3 g. In the same manner as in Example 1, a surface protective film laminate 5 having a protective layer (thickness: 100 μm) made of polyester-based polyurethane was obtained.

"Experiment 1: Plasticizer resistance" The release film was peeled from the prepared surface protective film 1 to surface protective film 5, and one drop of the plasticizer shown in Table 1 below was added to the protective layer. After 3 minutes and 14 hours of dripping, all the plasticizer was wiped off, the dripping site was visually confirmed, and evaluation was performed based on the following criteria. ○: Traces of droplets cannot be seen. △: The spot where the droplets are present is discolored or some swelling occurs. ×: Swelling occurs in the portion where the droplets are present.

[Table 1]

Typical bis (2-ethylhexyl) phthalate (DOP), bis (2-ethylhexyl) adipate (DOA), and diisononyl phthalate as representative plasticizers Examples (DINP) and Examples 1 and 2 in which the protective layer was made of polycarbonate polyurethane did not change color or swell after 3 minutes. Compared with the polyetherester-based plasticizer, Example 1 in which the polycarbonate-based polyol did not have a branched structure did not change color or swell after 14 hours. Compared with the polyetherester-based plasticizer, Example 2 in which the polycarbonate-based polyol had a branched structure showed no discoloration or swelling after 3 minutes, but a slight discoloration or swelling was confirmed after 14 hours.

Comparative Example 1 in which the protective layer was composed of an ether-based polyurethane was inferior in plasticizer resistance, and all the plasticizers showed some discoloration and swelling after 3 minutes. The plasticizer of Comparative Example 2 in which the protective layer was made of a lactone-based polyurethane was somewhat inferior in resistance. With respect to all the plasticizers, some discoloration and swelling were confirmed after 3 minutes. Among them, when compared with Comparative Example 1, Comparative Example 2 is excellent in plasticizer resistance. Compared to DOP, DOA, and DINP, which are typical plasticizers, Comparative Example 3, in which the protective layer is made of a polyester-based polyurethane, shows resistance equivalent to that of a polycarbonate-based polyurethane. Plasticizer properties. Among them, it is inferior to the polyether ester plasticizer compared to the polycarbonate polyurethane, and some discoloration and swelling can be confirmed after 3 minutes, and discoloration and swelling can be confirmed after 14 hours.

"Experiment 2: Silicon-based additive" 0.5 g of the silicon-based additive shown in Table 2 below was added to 100 g of the material composition used in Example 1, and the same method as in Example 1 was used. Made of surface protection film. The compatibility of the material composition and the silicon-based additive was evaluated by the following criteria. In addition, the total light transmittance and haze of the obtained surface protection film were measured by the following methods. In addition, for a compatibility evaluation of X, a surface protective film as a thermosetting material was not produced, and evaluations other than compatibility were not performed. The evaluation results are shown in Table 2.

"Evaluation method" ○: The material composition is compatible with the silicon-based additive. ×: The material composition is phase-separated from the silicon-based additive. The total light transmittance and haze were cut from a 5 cm square sample of the prepared surface protective film laminate, and the release film and peeling film were peeled off. The sample was set so that the surface of the protective layer became the light source side, and a haze meter ( (Manufactured by Nippon Denshoku Industries Co., Ltd., device name: NDH-2000).

Friction coefficient A 15 cm × 5 cm sample was cut from the prepared surface protective film laminate, and the release film and the peeling film were peeled off, and then the deviations of the static friction coefficient, dynamic friction coefficient, and dynamic friction coefficient of the protective layer side were measured under the following conditions. Surface property tester (manufactured by New East Science Co., Ltd., device name: TYPE14) Load: 153 g Speed: 700 mm / min Relative material: POM (front end shape curvature radius 0.65 mm) Angle: 75 degrees Static friction coefficient: Peak dynamic friction coefficient: The average dynamic friction coefficient deviation when moving 10 cm: The difference between the maximum and minimum dynamic friction coefficient when moving 10 cm

[Table 2]

It was confirmed that an additive made by adding a material compatible with the material composition as a silicon-based additive satisfies the total light transmittance and haze of the cured product that can be used as a surface protective film. In particular, as for the silicon-based additive composed of polyether-modified polydimethylsiloxane, the kinetic friction coefficient of the surface protective film is approximately half compared with that without the silicon-based additive, and the sliding property is excellent.

[Example 3] A surface protective film laminate 6 was obtained in the same manner as in Example 1 except that the thickness of the protective layer was set to 150 μm.

"Experiment 3: Load-displacement measurement" After the release film and the release film were peeled from the surface protective film laminate 6 obtained in Example 3, a protective layer having a thickness of 150 μm was attached to a measurement table via an adhesive layer. The amount of displacement when a load was applied to the protective layer was measured using a stylus made of polyacetal resin (POM) (manufactured by Wacom Co., Ltd., the tip of which was a hemispherical shape with a diameter of 1.4 mm). The measurement of the amount of displacement was performed from the time when a load of 0 gf was applied to the upper limit of 500 gf of the writing pressure of a normal person.

For comparison, a general copying paper (thickness: 0.09 mm, basis weight: 67 g / m ² ) was set as one sheet, two sheets overlapped, and three sheets overlapped. A ring-shaped weight (100 gf ) Press and similarly measure the amount of displacement when a load is applied to the center portion of the ring of the paper with the tip of a commercially available ballpoint pen (ball diameter 1.0 mm).

FIG. 5 shows a graph of load-displacement measurement. It was confirmed that it was sinking up to about 40 μm in one sheet of paper, sinking up to about 80 μm in two sheets of paper, and sinking up to about 108 μm in three sheets of paper. The protective layer (thickness: 150 μm) of the surface protective film of the present invention sinks up to approximately 76 μm, and this displacement amount is equivalent to 1.9 pieces of paper. That is, it was confirmed that when the surface protective film of the present invention is traced with a stylus pen, a writing feeling almost equivalent to that of writing on paper with a ballpoint pen can be obtained.

1‧‧‧ protective layer

2‧‧‧ transparent substrate film

3‧‧‧ Adhesive layer

4‧‧‧ release film

5‧‧‧ peeling film

10‧‧‧ surface protective film

20‧‧‧ transparent substrate

30‧‧‧Surface protection film laminate

40‧‧‧ flakes

40a‧‧‧Material composition

41‧‧‧casting machine

41a‧‧‧Head

42a‧‧‧First gap maintaining member

42b‧‧‧Second gap maintaining member

43a, 43b, 44‧‧‧ transport roller

45‧‧‧Auxiliary roller

46‧‧‧Heating device

47‧‧‧ conveyor belt

FIG. 1 is a view showing a surface protective film as an embodiment of the present invention. FIG. 2 is a view showing a state in which a surface protective film as an embodiment of the present invention is attached to a transparent substrate on the surface of a display. FIG. 3 is a view showing a surface protective film laminate as an embodiment of the present invention. FIG. 4 is a diagram illustrating a method for manufacturing a protective layer of a surface protective film. FIG. 5 is a diagram showing the results of displacement measurement in Experiment 3. FIG.

Claims (12)

A surface protection film comprising a protective layer made of a polycarbonate-based polyurethane on the outermost surface. The surface protection film according to item 1 of the scope of the patent application, which has at least three layers of the protection layer, the transparent substrate film, and the adhesive layer laminated in this order. The surface protective film according to item 1 or item 2 of the scope of the patent application, wherein the polycarbonate-based polyurethane is a material composition containing a polycarbonate-based polyol, an isocyanate, and an alcohol-based hardener. Hardened. The surface protection film according to any one of claims 1 to 3, wherein the protective layer includes a silicon-based additive. The surface protection film according to any one of claims 1 to 4, wherein the thickness of the protective layer is 50 μm or more and 300 μm or less. The surface protection film according to any one of claims 1 to 5 in the scope of patent application, wherein the haze value is 0.1% or more and 40% or less. A surface protective film laminate, characterized in that a mold release film is provided on the protective layer side surface area layer of the surface protective film according to any one of claims 1 to 6 in the patent application scope, and The surface area layer has a release film. A method for manufacturing a surface protective film, the surface protective film is characterized by having a protective layer made of polycarbonate-based polyurethane on the outermost surface, and the method for manufacturing the surface protective film is characterized by: A material composition containing a polycarbonate-based polyol, an isocyanate, an alcohol-based hardener, and a catalyst is fed into the gaps of the first and second gap maintaining members output by a pair of rollers disposed at a distance; and The composition is thermally cured while being held between the first and second gap maintaining members to form the protective layer. The method for manufacturing a surface protective film according to item 8 of the scope of application for a patent, wherein one of the first and second gap maintaining members is a transparent base film of a surface protective film. The method for manufacturing a surface protection film according to item 8 or item 9 of the scope of patent application, wherein the material composition includes a silicon-based additive. The method for manufacturing a surface protection film according to any one of claims 8 to 10, wherein one of the first and second gap maintaining members is a film not subjected to a release treatment, and One is a film subjected to a release treatment. The method for manufacturing a surface protection film according to any one of claims 8 to 11, wherein the other of the first and second gap maintaining members is a film having unevenness, and the method is The uneven surface holds the material composition.